A carburetor that's too small CFM-wise for an engine runs rich- - - -not lean. The airflow for any particular RPM is incorrect for the size of the carb. That's why any re-jetting needs to give less, not more fuel. Carburetors mix air and fuel by weight, not volume- - - -ideally, 14.7 parts air to 1 part fuel for a "stoichiometric" air/fuel ratio. Since atmospheric pressure at sea level is 14.7 pounds per square inch, it takes a 1 square inch column of air 100,000 feet tall to burn one pound of gasoline. Gas weighs a little less than 6 pounds per gallon. The laws of physics aren't "suggestions"!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!